A liquid crystal display (LCD) device includes a liquid circuit (LC) panel and a backlight unit. A typical backlight unit includes a plurality of light emitting diode (LED) light bars and a driving circuit of the LED light bars. Due to different LED light bars having different voltages, a voltage difference is generated between the different LED light bars, and the voltage difference is input to a constant current driving chip or other components, which increases temperature of the constant current driving chip and other components. One method is used to solve the above-mentioned problem: changing a duty cycle and current value of the each of the LED light bars, and maintaining an average current and voltage of each of the LED light bars to be same. For example, if voltage of one LED light bar is very low, the voltage of the one LED light bar can be increased by correspondingly increasing a current value of the one LED light bar, and simultaneously reducing a pulse-width modulation (PWM), and the voltage difference is reduced by adjusting the dirt cycle of the each of the LED light bars, and the power is kept constant.
However, when one or more LED lamps of the LED light has short-circuits, the above-mentioned method cannot determine whether the LED light bar short-circuits, thus, which is not able to provide effective short-circuit protection of the LED light bar.